Video encoding/decoding method and apparatus

Abstract

A video encoding method includes subjecting an input video image to motion compensated temporal filtering using a motion compensated temporal filter to produce a low-pass filtered image, quantizing a transform coefficient of the low-pass filtered image, encoding a quantized transform coefficient, calculating a weight to be given to a low-pass filter coefficient of a low-pass filter of the motion compensated temporal filter according to coarseness of quantization and a magnitude of a motion compensated error, and controlling a high band stopping characteristic of the low-pass filter according to the low-pass filter coefficient weighted by the weight, wherein the controlling controls the high band stopping characteristic of the low-pass filter to provide a positive correlation with respect to the quantization parameter and provide a negative correlation with respect to the magnitude of the motion compensated error.

1 . A video encoding method comprising: 
 subjecting an input video image to motion compensated temporal filtering using a motion compensated temporal filter including a low-pass filter to produce a low-pass filtered image;    quantizing a transform coefficient of the low-pass filtered image using a quantization parameter;    encoding a quantized transform coefficient;    calculating a weight to be given to a low-pass filter coefficient of the low-pass filter according to the quantization parameter and a magnitude of a motion compensated error occurring due to motion compensation in the motion compensated temporal filtering; and    controlling a high band stopping characteristic of the low-pass filter according to the low-pass filter coefficient weighted by the weight,    wherein the controlling controls the high band stopping characteristic of the low-pass filter to provide a positive correlation with respect to the quantization parameter and provide a negative correlation with respect to the magnitude of the motion compensated error.    
   
   
       2 . The method according to  claim 1 , wherein the controlling includes determining the low-pass filter coefficient based on the magnitude of the motion compensated error and a threshold value selected according to a predetermined table based on the quantization parameter by referring to the table to control the high band stopping characteristic of the low-pass filter.  
   
   
       3 . The method according to  claim 1 , wherein the motion compensated temporal filtering includes dividing hierarchically the image into a plurality of frames using the motion compensated temporal filter.  
   
   
       4 . The method according to  claim 1 , wherein the motion compensated temporal filter uses a Haar filter.  
   
   
       5 . The method according to  claim 1 , wherein the motion compensated temporal filtering includes performing a filter process by a lifting operation using a high-pass filter and the low-pass filter step by step.  
   
   
       6 . A video encoding method comprising: 
 performing motion compensated temporal filtering on an input video image with a motion compensated temporal filter including a low-pass filter to produce a low-pass filtered image;    detecting a magnitude of the motion compensated error occurring due to motion compensation in the motion compensated temporal filtering;    detecting a motion vector for motion compensation in the motion compensated temporal filtering;    selecting a threshold value every plural images or every image;    calculating a low-pass filter coefficient of the low-pass filter based on a magnitude of the motion compensated error, the motion vector and the threshold value;    controlling a high stopping characteristic of the low-pass filter according to the low-pass filter coefficient;    encoding the threshold value; and    multiplexing the encoded threshold value with a bit stream.    
   
   
       7 . A video decoding method comprising: 
 decoding a received bit stream to generate a decoded image, a quantization parameter and a threshold value for determining a high band stopping characteristic;    subjecting the decoded image to motion compensated temporal synthesis filtering using a motion compensated temporal synthesis filter including a synthesis low-pass filter to generate a synthesis low-pass filtered image;    controlling a high band stopping characteristic of the synthesis low-pass filter according to the high band stopping characteristic parameter; and    acquiring a motion compensated error from the received bit stream,    wherein the controlling controls the high band stopping characteristic of the low-pass filter to provide a positive correlation with respect to the quantization parameter and a negative correlation with respect to a magnitude of the motion compensated error.    
   
   
       8 . The method according to  claim 7 , wherein the controlling includes calculating a synthesis low-pass filter coefficient based on the magnitude of the motion compensated error and the threshold value selected according to a predetermined table based on a quantization parameter by referring to the table to control a high band stopping characteristic of the low-pass filter.  
   
   
       9 . A video decoding method comprising: 
 decoding a received bit stream to generate a decoded image, a quantization parameter, a motion vector and a threshold value for determining a high band stopping characteristic;    subjecting the decoded image to motion compensated temporal synthesis filtering using a motion compensated temporal synthesis filter including a synthesis low-pass filter to generate a synthesis low-pass filtered image;    controlling a high band stopping characteristic of the synthesis low-pass filter according to the threshold value; and    acquiring a motion compensated error from the receiving bit stream,    wherein the controlling includes controlling the high band stopping characteristic of the synthesis low-pass filter based on the motion compensated error, the threshold value and the motion vector.    
   
   
       10 . A video encoding apparatus of encoding an image, comprising: 
 a motion compensated temporal filter including a low-pass filter to subject a video image to motion compensated temporal filtering to produce a low-pass filtered image;    a quantizer to quantize a transform coefficient of the low-pass filtered image;    an encoder to encode a quantized transform coefficient,    a calculator to calculate a weight given to the low-pass filter coefficient according to a quantization parameter representing coarseness of quantization and a magnitude of a motion compensated error occurring due to motion compensation in the motion compensated temporal filtering; and    a controller to control a high band stopping characteristic of the low-pass filter according to a low-pass filter coefficient of the low-pass filter weighted by the weight,    wherein the controller controls the high band stopping characteristic of the low-pass filter to provide a positive correlation with respect to the quantization parameter and a negative correlation with respect to the magnitude of the motion compensated error.    
   
   
       11 . The apparatus according to  claim 10 , wherein the controller includes a table used for determining a threshold value and a determining unit configured to determine the low-pass filter coefficient based on the magnitude of the motion compensated error and a threshold value selected according to the table based on the quantization parameter by referring to the table to control the high band stopping characteristic of the low-pass filter.  
   
   
       12 . The apparatus according to  claim 10 , wherein the motion compensated temporal filter includes a dividing unit configured to divide hierarchically the video image into a plurality of frames.  
   
   
       13 . The apparatus according to  claim 10 , wherein the motion compensated temporal filter uses a Haar filter.  
   
   
       14 . The apparatus according to  claim 10 , wherein the motion compensated temporal filter includes a filter of performing a filter process by a lifting operation using a high-pass filter and the low-pass filter step by step.  
   
   
       15 . A video encoding apparatus of encoding an image, comprising: 
 a motion compensated temporal filter including a low-pass filter to subject a video image to motion compensated temporal filtering to generate a low-pass filtered image;    an error detector to detect a magnitude of a motion compensated error occurring due to motion compensation in the motion compensated temporal filtering;    a motion vector detector to detect a motion vector for motion compensation;    a threshold value generator to generate a threshold value;    a selector to select dynamically the threshold value every plural images or every image;    a calculator to calculate a low-pass filter coefficient of the low-pass filter based on the magnitude of the motion compensated error, the motion vector and the threshold value;    a controller to control a high band stopping characteristic of the low-pass filter according to the low-pass filter coefficient;    an encoder to encode the threshold value; and    a multiplexer to multiplex the encoded threshold value with a bit stream,    
   
   
       16 . A video decoding apparatus of decoding an image of a received bit stream, comprising: 
 a motion compensated temporal synthesis filter including a synthesis low-pass filter to subject an image to motion compensated temporal synthesis filtering to generate a synthesis low-pass filtered image;    a controller to control a high band stopping characteristic of the synthesis low-pass filter;    a quantization parameter detector to detect a quantization parameter from the received bit stream; and    an error detector to detect a motion compensated error from the received bit stream, wherein    the controller controls the high band stopping characteristic of the low-pass filter to provide a positive correlation with respect to the quantization parameter and a negative correlation with respect to the magnitude of the motion compensated error.    
   
   
       17 . The apparatus according to  claim 16 , wherein the motion compensated temporal synthesis filter includes a composite unit configured to composite a plurality of frames of the decoded image, which are divided hierarchically.  
   
   
       18 . The apparatus according to  claim 16 , wherein the motion compensated temporal synthesis filter uses a Haar filter.  
   
   
       19 . The apparatus according to  claim 16 , wherein the motion compensated temporal synthesis filter includes a filter to perform a filter process by a lifting operation using a high-pass filter and the low-pass filter step by step.  
   
   
       20 . A video decoding apparatus of decoding an image of a received bit stream, comprising: 
 a decoder to decode a received bit stream to generate a decoded image, a quantization parameter and a threshold value for determining a high band stopping characteristic;    a motion compensated temporal synthesis filter including a synthesis low-pass filter to subject the decoded image to motion compensated temporal synthesis filtering to generate a synthesis low-pass filtered image;    a controller to control a high band stopping characteristic of the synthesis low-pass filter; and    an error detector to detect a motion compensated error from the received bit stream, wherein    the controller controls a high band stopping characteristic of the synthesis low-pass filter based on a magnitude of the motion compensated error, the motion vector and the threshold value.